// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Mark Borgerding mark a borgerding net
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

namespace Eigen {

namespace internal {

// FFTW uses non-const arguments
// so we must use ugly const_cast calls for all the args it uses
//
// This should be safe as long as
// 1. we use FFTW_ESTIMATE for all our planning
//       see the FFTW docs section 4.3.2 "Planner Flags"
// 2. fftw_complex is compatible with std::complex
//    This assumes std::complex<T> layout is array of size 2 with real,imag
template<typename T>
inline T*
fftw_cast(const T* p)
{
	return const_cast<T*>(p);
}

inline fftw_complex*
fftw_cast(const std::complex<double>* p)
{
	return const_cast<fftw_complex*>(reinterpret_cast<const fftw_complex*>(p));
}

inline fftwf_complex*
fftw_cast(const std::complex<float>* p)
{
	return const_cast<fftwf_complex*>(reinterpret_cast<const fftwf_complex*>(p));
}

inline fftwl_complex*
fftw_cast(const std::complex<long double>* p)
{
	return const_cast<fftwl_complex*>(reinterpret_cast<const fftwl_complex*>(p));
}

template<typename T>
struct fftw_plan
{};

template<>
struct fftw_plan<float>
{
	typedef float scalar_type;
	typedef fftwf_complex complex_type;
	fftwf_plan m_plan;
	fftw_plan()
		: m_plan(NULL)
	{
	}
	~fftw_plan()
	{
		if (m_plan)
			fftwf_destroy_plan(m_plan);
	}

	inline void fwd(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_1d(nfft, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft(m_plan, src, dst);
	}
	inline void inv(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_1d(nfft, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft(m_plan, src, dst);
	}
	inline void fwd(complex_type* dst, scalar_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_r2c_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft_r2c(m_plan, src, dst);
	}
	inline void inv(scalar_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_c2r_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft_c2r(m_plan, src, dst);
	}

	inline void fwd2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_2d(n0, n1, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft(m_plan, src, dst);
	}
	inline void inv2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftwf_plan_dft_2d(n0, n1, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwf_execute_dft(m_plan, src, dst);
	}
};
template<>
struct fftw_plan<double>
{
	typedef double scalar_type;
	typedef fftw_complex complex_type;
	::fftw_plan m_plan;
	fftw_plan()
		: m_plan(NULL)
	{
	}
	~fftw_plan()
	{
		if (m_plan)
			fftw_destroy_plan(m_plan);
	}

	inline void fwd(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_1d(nfft, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft(m_plan, src, dst);
	}
	inline void inv(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_1d(nfft, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft(m_plan, src, dst);
	}
	inline void fwd(complex_type* dst, scalar_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_r2c_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft_r2c(m_plan, src, dst);
	}
	inline void inv(scalar_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_c2r_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft_c2r(m_plan, src, dst);
	}
	inline void fwd2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_2d(n0, n1, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft(m_plan, src, dst);
	}
	inline void inv2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftw_plan_dft_2d(n0, n1, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftw_execute_dft(m_plan, src, dst);
	}
};
template<>
struct fftw_plan<long double>
{
	typedef long double scalar_type;
	typedef fftwl_complex complex_type;
	fftwl_plan m_plan;
	fftw_plan()
		: m_plan(NULL)
	{
	}
	~fftw_plan()
	{
		if (m_plan)
			fftwl_destroy_plan(m_plan);
	}

	inline void fwd(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_1d(nfft, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft(m_plan, src, dst);
	}
	inline void inv(complex_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_1d(nfft, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft(m_plan, src, dst);
	}
	inline void fwd(complex_type* dst, scalar_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_r2c_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft_r2c(m_plan, src, dst);
	}
	inline void inv(scalar_type* dst, complex_type* src, int nfft)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_c2r_1d(nfft, src, dst, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft_c2r(m_plan, src, dst);
	}
	inline void fwd2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_2d(n0, n1, src, dst, FFTW_FORWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft(m_plan, src, dst);
	}
	inline void inv2(complex_type* dst, complex_type* src, int n0, int n1)
	{
		if (m_plan == NULL)
			m_plan = fftwl_plan_dft_2d(n0, n1, src, dst, FFTW_BACKWARD, FFTW_ESTIMATE | FFTW_PRESERVE_INPUT);
		fftwl_execute_dft(m_plan, src, dst);
	}
};

template<typename _Scalar>
struct fftw_impl
{
	typedef _Scalar Scalar;
	typedef std::complex<Scalar> Complex;

	inline void clear() { m_plans.clear(); }

	// complex-to-complex forward FFT
	inline void fwd(Complex* dst, const Complex* src, int nfft)
	{
		get_plan(nfft, false, dst, src).fwd(fftw_cast(dst), fftw_cast(src), nfft);
	}

	// real-to-complex forward FFT
	inline void fwd(Complex* dst, const Scalar* src, int nfft)
	{
		get_plan(nfft, false, dst, src).fwd(fftw_cast(dst), fftw_cast(src), nfft);
	}

	// 2-d complex-to-complex
	inline void fwd2(Complex* dst, const Complex* src, int n0, int n1)
	{
		get_plan(n0, n1, false, dst, src).fwd2(fftw_cast(dst), fftw_cast(src), n0, n1);
	}

	// inverse complex-to-complex
	inline void inv(Complex* dst, const Complex* src, int nfft)
	{
		get_plan(nfft, true, dst, src).inv(fftw_cast(dst), fftw_cast(src), nfft);
	}

	// half-complex to scalar
	inline void inv(Scalar* dst, const Complex* src, int nfft)
	{
		get_plan(nfft, true, dst, src).inv(fftw_cast(dst), fftw_cast(src), nfft);
	}

	// 2-d complex-to-complex
	inline void inv2(Complex* dst, const Complex* src, int n0, int n1)
	{
		get_plan(n0, n1, true, dst, src).inv2(fftw_cast(dst), fftw_cast(src), n0, n1);
	}

  protected:
	typedef fftw_plan<Scalar> PlanData;

	typedef Eigen::numext::int64_t int64_t;

	typedef std::map<int64_t, PlanData> PlanMap;

	PlanMap m_plans;

	inline PlanData& get_plan(int nfft, bool inverse, void* dst, const void* src)
	{
		bool inplace = (dst == src);
		bool aligned = ((reinterpret_cast<size_t>(src) & 15) | (reinterpret_cast<size_t>(dst) & 15)) == 0;
		int64_t key = ((nfft << 3) | (inverse << 2) | (inplace << 1) | aligned) << 1;
		return m_plans[key];
	}

	inline PlanData& get_plan(int n0, int n1, bool inverse, void* dst, const void* src)
	{
		bool inplace = (dst == src);
		bool aligned = ((reinterpret_cast<size_t>(src) & 15) | (reinterpret_cast<size_t>(dst) & 15)) == 0;
		int64_t key = (((((int64_t)n0) << 30) | (n1 << 3) | (inverse << 2) | (inplace << 1) | aligned) << 1) + 1;
		return m_plans[key];
	}
};

} // end namespace internal

} // end namespace Eigen
